This application relates to optical communication ring networks.
Optical ring networks can be built using a single optical fiber ring path to optically link optical communication nodes. Either uni-directional or bi-directional optical communication traffic can be provided in such single-fiber optical ring networks. Various optical wavelength division multiplexing (WDM) techniques can be used to increase the number optical wavelengths in a single fiber to increase the optical communication capacity, such as dense WDM (DWDM) networks. Optical ring networks can have various applications, including the access part of a network or the backbone of a network such as interconnecting central offices. Optical ring networks can be implemented to provide a protection switch as a “self-healing” mechanism to maintain continuous operation when an optical break occurs in the optical ring and can also allow for relative ease in adding and deleting nodes on the optical ring. WDM or DWDM optical ring networks can be implemented with all optical add/drop nodes on the ring without expensive O-E-O regenerator so that nodes are connected directly by multiple WDM or DWDM wavelengths to offer increased capacity, reduced timing jitter, and improved signal latency and to allow for scalability, at a reduced cost. The cost of optical fiber deployment in a ring topology can be less than that in a mesh topology. Due to these and other features of optical ring networks, optical ring networks have been widely deployed in metro and regional local area networks (LANs) for both data communication systems such as a token-ring LAN and Fiber Distributed Data Interface (FDDI) LAN) and telecom systems such as SONET/SDH optical networks.